Page 301 of 473

300 Operation
Engine compartment
Unscrew filler cap1 from filler neck.
Add engine oil as required.
Be careful not to overfill with oil.
Be careful not to spill any oil when adding.
Avoid environmental damage caused by oil
entering the ground or water.
Screw filler cap1 back on filler neck.
For more information on engine oil, see
“Technical data” (
page 443) and
(
page 445).
Transmission fluid level*
Vehicles with automatic transmission*:
The transmission fluid level does not need
to be checked. If you notice transmission
fluid loss or gear shifting malfunctions,
have an authorized Mercedes-Benz Center
check the transmission.Coolant level
The engine coolant is a mixture of water
and anticorrosion/antifreeze. To check
the coolant level, the vehicle must be
parked on level ground and the engine
must be cool.
!Excess oil must be siphoned or drained off.
It could cause damage to the engine and
emission control system not covered by the
Mercedes-Benz Limited Warranty.Warning!G
In order to avoid any potentially serious
burns:
Use extreme caution when opening the
hood if there are any signs of steam or
coolant leaking from the cooling system,
or if the coolant temperature gauge indi-
cates that the coolant is overheated.
Do not remove pressure cap on coolant
reservoir if coolant temperature is
above 158°F (70°C). Allow engine to
cool down before removing cap. The
coolant reservoir contains hot fluid and
is under pressure.
Page 302 of 473
301 Operation
Engine compartment
The coolant expansion tank is located on
the passenger side of the engine compart-
ment.
SLK 350 (example illustration)
1Coolant expansion tank
2Cap
3Marking bar in the expansion tank
Using a rag, turn cap2 slowly approx-
imately one half turn counterclockwise
to release any excess pressure.
Continue turning cap2 counterclock-
wise and remove it.
The coolant level is correct if the level
for cold coolant: reaches marking
bar3 in expansion tank1
for warm coolant: is approximately
0.6 in (1.5 cm) higher
Add coolant as required.
Replace and tighten cap2.
For more information on coolant, see
“Coolants” (
page 448).
Using a rag, slowly open the cap approx-
imately 1/2turn to relieve excess pres-
sure. If opened immediately, scalding
hot fluid and steam will be blown out un-
der pressure.
Do not spill antifreeze on hot engine
parts. Antifreeze contains ethylene
glycol which may burn if it comes into
contact with hot engine parts.
Page 369 of 473
368 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
•Coolant
Stop, turn engine
offThe coolant is too hot.
Among other possible causes,
the poly-V-belt could be broken.Stop the vehicle in a safe location or as soon as it is
safe to do so.
Turn off the engine.
Apply the parking brake (page 59).
Check the poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise, the engine will
overheat due to an inoperative water pump which
may result in damage to the engine. Contact an
authorized Mercedes-Benz Center.
If it is intact:
Wait for the message to disappear before restarting
the engine.
Doing otherwise could result in serious engine
damage that is not covered by the Mercedes-Benz
Limited Warranty.
(Continued on next page)
Page 370 of 473

369 Practical hints
What to do if …
During severe operating conditions, e.g.
stop-and-go traffic, the coolant tempera-
ture may rise close to 248°F (120°C).
Display symbolDisplay messagePossible cause/consequencePossible solution
Observe the coolant temperature display
(
page 127).
If the temperature rises again:
Contact an authorized Mercedes-Benz
Center immediately.
Warning!G
Driving when your engine is overheated can
cause some fluids which may have leaked
into the engine compartment to catch fire.
You could be seriously burned.
Steam from an overheated engine can cause
serious burns and can occur just by opening
the hood. Stay away from the engine if you
see or hear steam coming from it.
Turn off the engine, get out of the vehicle
and do not stand near the vehicle until the
engine has cooled down.
!The engine should not be operated with the
coolant temperature above 248°F (120°C).
Doing so may cause serious engine damage
which is not covered by the Mercedes-Benz
Limited Warranty.
Page 371 of 473

370 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
•The cooling fan for the coolant is
malfunctioning.Observe the coolant temperature display
(
page 127).
If the coolant temperature is below 120°C,
you may continue driving to the nearest
specialist workshop.
Avoid heavy loads on the engine (e.g. by
driving uphill) as well as stop-and-go traffic.
Have the fan replaced as soon as possible.
/Top up coolant
See Oper. ManualThe coolant level is too low.Add coolant (page 300).
Comply with all warnings while doing so.
If you have to add coolant frequently,
have the cooling system checked by an au-
thorized Mercedes-Benz Center.
Warning!G
Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. You could be seriously burned.
!Do not ignore the low engine coolant level
warning. Extended driving with this message and
symbol displayed may cause serious engine
damage not covered by the Mercedes-Benz
Limited Warranty. Do not drive without sufficient
amount of coolant in the cooling system. The
engine will overheat, causing major engine
damage.
Page 428 of 473
427 Technical data
Parts service
Warranty coverage
Identification labels
Layout of poly-V-belt drive
Engine
Rims and tires
Electrical system
Main Dimensions
Weights
Fuels, coolants, lubricants, etc.
Page 444 of 473

443 Technical data
Fuels, coolants, lubricants, etc.
Fuels, coolants, lubricants, etc.
Capacities
Vehicle components and their respective
lubricants must match. Therefore, only use
products tested and approved by
Mercedes-Benz.
Please refer to the Factory Approved
Service Products pamphlet (USA only), or
inquire at an authorized Mercedes-Benz
Center.
Warning!G
Comply with all valid regulations with
respect to handling, storing and disposing
of service fluids. Otherwise you could
endanger persons or the environment.
Keep service fluids out of the reach of
children.
For health reasons, you should prevent
service fluids from coming into direct
contact with you skin or clothing.
If a service fluid is swallowed, contact a
physician immediately.
ModelCapacityFuels, coolants, lubricants etc.
Engine with oil filterAll models8.5 US qt (8.0 l)Approved engine oils
Automatic transmission*SLK 280, SLK 3509.5 US qt (9.0 l)MB Automatic Transmission Fluid
SLK 55 AMG9.2 US qt (8.7 l)
Manual transmissionSLK 280, SLK 3501.6 US qt (1.5 l)MB Manual Transmission Oil
Rear axleSLK 2801.1 US qt (1.0 l)Hypoid gear oil SAE 85 W 90
SLK 3501.2 US qt (1.1 l)
SLK 55 AMG1.3 US qt (1.2 l)
Page 446 of 473

445 Technical data
Fuels, coolants, lubricants, etc.
Engine oils
Engine oils are specifically tested for
their suitability in our engines and durabil-
ity for our service intervals. Therefore, only
use approved engine oils and oil filters
required for vehicles with
Maintenance System. For a listing of ap-
proved engine oils and oil filters, refer to
the Factory Approved Service Products
pamphlet (USA only), or contact an
authorized Mercedes-Benz Center.Engine oil additivesAir conditioning refrigerant
R-134a (HFC) refrigerant and special
PAG lubricating oil are used in the air con-
ditioning system.
!Using engine oils and oil filters of specifica-
tion other than those expressly required for the
Maintenance System, or changing of oil and oil
filter at change intervals longer than those called
for by the Maintenance System will result in
engine or emission control system damage
not covered by the Mercedes-Benz Limited
Warranty.
Please follow Maintenance System recommen-
dations for scheduled oil changes. Failure to do
so will result in engine or emission control sys-
tem damage not covered by the Mercedes-Benz
Limited Warranty.
!Do not blend oil additives with engine oil.
They may damage the engine. Damage or mal-
functions resulting from blending oil additives
are not covered by the Mercedes-Benz Limited
Warranty.
!Never use R-12 (CFC) or mineral-based
lubricating oil, otherwise damage to the system
will occur.